Siskiyou aster

(Symphyotrichum lanceolatum var. hesperium)

Conservation Status

 

No image available

  IUCN Red List

not listed

     
  NatureServe

NNR - Unranked

SNR - Unranked

     
  Minnesota

not listed

     
           
Wetland Indicator Status
     
  Great Plains

FACW - Facultative wetland

     
  Midwest

FAC - Facultative

     
  Northcentral & Northeast

FACW - Facultative wetland

     
           
 
Description
 
 

Siskiyou aster (var. hesperium) is a 12 to 60 tall, erect, perennial forb that rises on a single stem from a long, slender, branched rhizome. It sometimes forms large, dense colonies.

The stem is erect, straight, stout, and grooved. It is unbranched below the middle. It is green at first, eventually becoming brown and woody near the base. Above the middle it usually has many, sometimes just a few, spreading, ascending branches. It is usually hairless toward the bottom and may have sparsely to moderately dense, longitudinal lines of short, white, spreading or curled hairs toward the top.

Basal leaves are stalkless. The leaf blades are thin, inversely lance-shaped or inversely egg-shaped, up to 3 long, and up to ¾ wide. They are tapered at the base, and rounded or angled at the tip. There is a short, sharp, abrupt point at the tip. The upper and lower surfaces are hairless. The margins are toothed with rounded, forward-pointing teeth, and have a fringe of hairs. Basal leaves are usually withered at flowering time.

Stem leaves are alternate. Lower stem leaves are stalkless or on short, winged, poorly differentiated leaf stalks (petioles). The petioles are winged and sheath the stem at the base. The leaf blades are linear lance-shaped to inversely lance-shaped, 2 to 6 long, and to ¾ wide. They are wedge-shaped or tapered and sometimes slightly expanded at the base, but they do not clasp the stem. They taper to a point at the tip. The upper and lower surfaces are hairless. The margins are shallowly toothed. The leaves become progressively smaller, narrower, and shorter-stalked as they approach the middle of the stem. Middle and upper stem leaves are untoothed. Upper stem leaves are stalkless, linear, and 1¼ to 4 long, not much smaller than the middle stem leaves. Lower stem and sometimes some of the larger middle stem leaves are withered by flowering time.

The inflorescence is a branched cluster (panicle) at the end of the stem. The primary branches of the panicle are relatively sparse, loosely ascending or spreading, and sometimes solitary or more often clustered near the end of the vegetative branch. The flower heads are closely spaced, appearing dense, on lateral, secondary branches. The heads are usually oriented in various directions, sometimes oriented toward the top of the branch. The flower heads are on 3 16 to 2 long flower stalks (peduncles). They are usually subtended by leaf-like appendages (bracts). The leaves on the flowering branches are often longer than the peduncles, but are much smaller than the upper stem leaves.

The individual flower head is medium-sized, ¾ to 1 in diameter. The whorl of bracts (phyllaries) at the base of the flower head form a cup-shaped, to ¼ long cup (involucre). The phyllaries are arranged in 3 to 5 appressed to slightly spreading, overlapping series. They do not have a spine-like tip. Phyllaries in the outer series are as long or longer than those of the inner series. There are 18 to 45 ray florets and 18 to 52 disk florets. The ray florets are in 1 or 2 series. They are to long and usually pale to dark purplish-blue, sometimes white. The disk florets are yellow at first, eventually becoming purple. The flowers are not fragrant.

The fruit is a dry seed capsule (cypsela) with a tuft of bristles (pappus) attached to the end. The cypsela is egg-shaped, gray to tan, and 1 32to 1 16 long. It has 4 or 5 longitudinal ribs. The pappus is white to off-white.

 
     
 

Height

 
 

12 to 60

 
     
 

Flower Color

 
 

Purplish-blue

 
     
 

Similar Species

 
 

Eastern panicled aster (Symphyotrichum lanceolatum ssp. lanceolatum) heads are not subtended by large, leaf-like bracts. Phyllaries in the outer series are to as long as those of the inner series.

 
     
 
Habitat
 
 

Moist. Stream banks, wet meadows, and ditches. Full sun to partial shade.

 
     
 
Ecology
 
 

Flowering

 
 

July to October

 
     
 
Use
 
 

 

 
     
 
Distribution
 
 

Distribution Map

 

Sources

3, 28.

 
  1/31/2014      
         
 

Nativity

 
 

Native

 
         
 

Occurrence

 
 

 

 
         
 
Taxonomy
 
  Kingdom Plantae (green algae and land plants)  
  Subkingdom Viridiplantae (green plants)  
  Infrakingdom Streptophyta (land plants and green algae)  
  Superdivision Embryophyta (land plants)  
  Division Tracheophyta (vascular plants)  
  Subdivision Spermatophytina (seed plants)  
  Class Magnoliopsida (dicots)  
  Superorder Asteranae  
 

Order

Asterales (sunflowers, bellflowers, fanflowers, and allies)  
 

Family

Asteraceae (sunflowers, daisies, asters, and allies)  
  Subfamily Asteroideae  
  Supertribe Asterodae  
  Tribe Astereae (asters and allies)  
  Genus Symphyotrichum (aster)  
  Subgenus Symphyotrichum  
  Section Symphyotrichum  
  Species Symphyotrichum lanceolatum (white panicled aster)  
  Subspecies Symphyotrichum lanceolatum ssp. hesperium (Siskiyou aster)  
       
 

This and other asters were formerly place in the genus Aster. That genus was problematic, in that it did not include just one common ancestor with all of its lineal descendants and no others – it was not monophyletic. In 1994, the genus Symphyotrichum was resurrected to include most North American asters formerly in the genus Aster.

This is a variety of a subspecies, and some sources list it as Symphyotrichum lanceolatum ssp. hesperium var. hesperium. The ICN (International Code of Nomenclature for algae, fungi, and plants), the rules governing the naming of plant species, makes it clear that this is not correct. Following ICN rules, a taxa “may also be referred to” with the inclusion of the intervening name (in this case, “ssp. hesperium”), but that does not constitute a formal name.

 
       
 

Subordinate Taxa

 
 

 

 
       
 

Synonyms

 
 

Aster hesperius

Aster laetevirens

Aster lanceolatus ssp. hesperius

Aster hesperius var. laetevirens

Aster hesperius var. wootonii

Aster wootonii

Aster osterhoutii

Symphyotrichum hesperium

Symphyotrichum lanceolatum ssp. hesperium var. hesperium

 
       
 

Common Names

 
 

panicled aster

Siskiyou aster

tall white aster

western panicle aster

white panicle aster

 
       

 

 

 

 

 

 

 

 

Glossary

Bract

Modified leaf at the base of a flower stalk or flower cluster.

 

Clasping

Describing a leaf that wholly or partly surrounds the stem but does not fuse at the base.

 

Cypsela

A dry, one-chambered, single-seeded fruit, formed from a single carpel, with the seed attached to the membranous outer layer (wall) only by the seed stalk; the wall, formed from the wall of the inferior ovary and also from other tissues derived from the receptacle or hypanthium, does not split open at maturity, but relies on decay or predation to release the contents.

 

Involucre

A whorl of bracts beneath or surrounding a flower or flower cluster.

 

Linear

Long, straight, and narrow, with more or less parallel sides, like a blade of grass.

 

Panicle

A pyramidal inflorescence with a main stem and branches. Flowers on the lower, longer branches mature earlier than those on the shorter, upper ones.

 

Pappus

The modified calyx composed of awns, scales, bristles, or feather-like hairs in plants of the Asteraceae family.

 

Petiole

The stalk of a leaf blade or compound leaf that attaches the leaf blade to the stem.

 

Phyllary

An individual bract within the involucre of a plant in the Asteraceae family.

 

Rhizome

A horizontal, usually underground stem. It serves as a reproductive structure, producing roots below and shoots above at the nodes.

 

Sheath

The lower part of the leaf that surrounds the stem.

 

Winged leaf stalk

A leaf stalk with a leaf-like or membrane-like extension along both sides.

 

       
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